Quantum Computing

Gone are the days of Classical Computers that are designed using transistors. The era of Quantum Computing has dawned. A quantum computer works under the quantum mechanical principles of superposition and entanglement. In a classical machine data is stored in bits, whereas in a quantum machine data is stored as qubits (Quantum Binary Digits). The basic idea of quantum computing is that the properties of quantum can be used to represent data and quantum mechanics can be used to perform operations on this data.

The efficient use of quantum machines will be in the field of cryptography for cryptanalysis. The Shor's algorithm which aims to solve or crack the RSA algorithm will work perfectly in polynomial time if quantum computers are used. The RSA algorithm can be cracked if we are able to factorise a number 'n' into the two primes that constitute the product. The Shor's algorithm finds those two numbers in polynomial time while the other algorithms can solve only in exponential time.

The problems solvable by quantum computers area called BQP, "Bounded Error, Quantum Polynomial time". Quantum computers run only "probabilistic" algorithms. A quantum computer is said to "solve" a problem if for every instance the solution it provides is right with high probability. Even though, quantum computers are faster than the classical computers, quantum machines can't solve problems that are not solvable by classical machines. Since the quantum machines can be simulated using "Turing Machines", quantum computers cannot solve undecidable problems. But, a realization of quantum computers, which is still in the research phase, will add a new dimension to the Computer Science.